diff --git a/DESCRIPTION b/DESCRIPTION
index 2263a84..5a8ae3b 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -23,12 +23,11 @@ Suggests:
 Description: Tools to create and modify network objects.  The network class can represent a range of relational data types, and supports arbitrary vertex/edge/graph attributes.
 License: GPL (>=2)
 URL: https://statnet.org/
-RoxygenNote: 7.3.1
+RoxygenNote: 7.3.2
 Roxygen: list(markdown = TRUE)
 Collate:
     'access.R'
     'as.edgelist.R'
-    'assignment.R'
     'coercion.R'
     'constructors.R'
     'dataframe.R'
diff --git a/R/access.R b/R/access.R
index 237d805..f211d91 100644
--- a/R/access.R
+++ b/R/access.R
@@ -146,9 +146,7 @@
 add.edge<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, edge.check=FALSE, ...){
   xn<-substitute(x)
   UseMethod("add.edge") 
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x) 
 } 
 
@@ -156,9 +154,7 @@ add.edge<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, edge.check=FA
 #' @export
 add.edge.network<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, edge.check=FALSE, ...){ 
   xn<-substitute(x)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   x<-.Call(addEdge_R,x,tail,head,names.eval,vals.eval,edge.check)
   invisible(x)
 }
@@ -170,9 +166,7 @@ add.edge.network<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, edge.
 add.edges<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, ...){
   xn<-substitute(x)
   UseMethod("add.edges") 
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x) 
 } 
 
@@ -204,9 +198,7 @@ add.edges.network<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, ...)
   #Pass the inputs to the C side
   xn<-substitute(x)
   x<-.Call(addEdges_R,x,tail,head,names.eval,vals.eval,edge.check)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
 
@@ -281,9 +273,7 @@ add.edges.network<-function(x, tail, head, names.eval=NULL, vals.eval=NULL, ...)
 add.vertices<-function(x, nv, vattr=NULL, last.mode=TRUE, ...){
   xn<-substitute(x)
   UseMethod("add.vertices") 
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x) 
 }
 
@@ -306,9 +296,7 @@ add.vertices.network<-function(x, nv, vattr=NULL, last.mode=TRUE, ...){
   #Perform the addition
   xn<-substitute(x)
   if(nv>0){
-    if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-      on.exit(eval.parent(call('<-',xn,x)))
-    }
+    on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
     if(last.mode||(!is.bipartite(x))){
       x<-.Call(addVertices_R,x,nv,vattr)
     }else{
@@ -495,9 +483,7 @@ delete.edge.attribute.network <- function(x, attrname, ...) {
   #Remove the edges
   xn<-substitute(x)
   x<-.Call(deleteEdgeAttribute_R,x,attrname)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
  
@@ -578,9 +564,7 @@ delete.edges.network <- function(x, eid, ...) {
       stop("Illegal edge in delete.edges.\n")
     #Remove the edges
     x<-.Call(deleteEdges_R,x,eid)
-    if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-      on.exit(eval.parent(call('<-',xn,x)))
-    }
+    on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   }
   invisible(x)
 }
@@ -599,9 +583,7 @@ delete.network.attribute.network <- function(x, attrname, ...){
   #Remove the edges
   xn<-substitute(x)
   x<-.Call(deleteNetworkAttribute_R,x,attrname)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
 
@@ -621,9 +603,7 @@ delete.vertex.attribute.network <- function(x, attrname, ...) {
   if(network.size(x)>0){
     xn<-substitute(x)
     x<-.Call(deleteVertexAttribute_R,x,attrname)
-    if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-      on.exit(eval.parent(call('<-',xn,x)))
-    }
+    on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   }
   invisible(x)
 }
@@ -650,9 +630,7 @@ delete.vertices.network <- function(x, vid, ...) {
       set.network.attribute(x,"bipartite",m1v-sum(vid<=m1v))
     }
     x<-.Call(deleteVertices_R,x,vid)
-    if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-      on.exit(eval.parent(call('<-',xn,x)))
-    }
+    on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   }
   invisible(x)
 }
@@ -1873,9 +1851,7 @@ permute.vertexIDs<-function(x,vids){
   #Return the permuted graph
   xn<-substitute(x)
   x<-.Call(permuteVertexIDs_R,x,vids)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
 
@@ -1971,9 +1947,7 @@ set.edge.attribute.network <- function(x, attrname, value, e=seq_along(x$mel), .
       #Do the deed, call the set multiple version
       x<-.Call(setEdgeAttributes_R,x,attrname,value,e)
     }
-    if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-      on.exit(eval.parent(call('<-',xn,x)))
-    }
+    on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   }
   invisible(x)
 }
@@ -2010,9 +1984,7 @@ set.edge.value.network <- function(x, attrname, value, e = seq_along(x$mel), ...
   #Do the deed
   xn<-substitute(x)
   x<-.Call(setEdgeValue_R,x,attrname,value,e)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
 
@@ -2042,9 +2014,7 @@ set.network.attribute.network <- function(x, attrname, value, ...) {
   #Do the deed
   xn<-substitute(x)
   x<-.Call(setNetworkAttribute_R,x,attrname,value)
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
 
@@ -2180,8 +2150,6 @@ set.vertex.attribute.network <- function(x, attrname, value, v = seq_len(network
   } # end setting multiple values
   #Do the deed
   
-  if(.validLHS(xn,parent.frame())){  #If x not anonymous, set in calling env 
-    on.exit(eval.parent(call('<-',xn,x)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',xn,x)),error=identity))
   invisible(x)
 }
diff --git a/R/assignment.R b/R/assignment.R
deleted file mode 100644
index 4019beb..0000000
--- a/R/assignment.R
+++ /dev/null
@@ -1,63 +0,0 @@
-######################################################################
-#
-# assignment.R
-#
-# Written by Carter T. Butts <buttsc@uci.edu>; portions contributed by
-# David Hunter <dhunter@stat.psu.edu> and Mark S. Handcock
-# <handcock@u.washington.edu>.
-#
-# Last Modified 11/26/19
-# Licensed under the GNU General Public License version 2 (June, 1991)
-# or greater
-#
-# Part of the R/network package
-#
-# This file contains various routines for the assignment of network objects
-# into calling environments. These are internal functions and not to be used
-# by the package users.
-#
-# Contents:
-#
-#   .findNameInSubsetExpr
-#   .validLHS
-#
-######################################################################
-
-
-# Recursively traverse the parse tree of the expression x, ensuring that it is
-# a valid subset expresssion, and return the name associated with the expression.
-#
-.findNameInSubsetExpr <- function(x){
-  if (inherits(x,'call')){
-    # Ensure call is a subset function, one of $, [, or [[
-    if(!(deparse(x[[1]]) %in% c('$','[','[['))) return(NA)
-
-    # Make sure arguments are clean
-    xns <- lapply(x[2:length(x)],.findNameInSubsetExpr)
-    if (any(is.na(xns))) return(NA)
-      
-    # Possible name found
-    return(xns[[1]])
-  }
-  else if (inherits(x,'name'))
-    return(deparse(x))
- 
-  NULL 
-}
-
-# Return TRUE if x is a valid left-hand-side object that can take a value
-
-.validLHS <- function(x,ev){
-  xn <- .findNameInSubsetExpr(x)
-  # There are valid expressions for which we don't want to assign into the caller's env.
-  # For instance, when a user executes z<-add.edges(x+y), then the user obviously
-  # doesn't want x+y to be assigned. Rather he's using them as temporaries to obtain
-  # z. OTOH we don't want someone doing something obtuse like add.edges(x[sample(...)])
-  # In the first case, it's not wrong to end up here, but in the second case we would
-  # like to warn the user. But we're not going to at this point.
-  #warning('Cannot make assignment into ',deparse(x))
-  if (!is.null(xn) && !is.na(xn) && exists(xn,envir=ev))
-    return(TRUE)
-  else
-    return(FALSE)
-}
diff --git a/R/constructors.R b/R/constructors.R
index a633d1f..3a8f8d2 100644
--- a/R/constructors.R
+++ b/R/constructors.R
@@ -203,9 +203,7 @@ network.bipartite<-function(x, g, ignore.eval=TRUE, names.eval=NULL, ...){
     add.edges(g, as.list(1+e%%n), as.list(1+e%/%n),
               names.eval=en, vals.eval=ev, ...)
   #Patch up g on exit for in-place modification
-  if(.validLHS(gn,parent.frame())){
-    on.exit(eval.parent(call('<-',gn,g)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',gn,g)),error=identity))
   invisible(g)
 }
 
@@ -276,9 +274,7 @@ network.adjacency<-function(x, g, ignore.eval=TRUE, names.eval=NULL, ...){
     add.edges(g, as.list(1+e%%n), as.list(1+e%/%n),
               names.eval=en, vals.eval=ev, ...)
   #Patch up g on exit for in-place modification
-  if(.validLHS(gn,parent.frame())){
-    on.exit(eval.parent(call('<-',gn,g)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',gn,g)),error=identity))
   invisible(g)
 }
 
@@ -342,9 +338,7 @@ network.edgelist<-function(x, g, ignore.eval=TRUE, names.eval=NULL, ...){
     g<-add.edges(g,as.list(x[,1]),as.list(x[,2]),edge.check=edge.check)
   }
   #Patch up g on exit for in-place modification
-  if(.validLHS(gn,parent.frame())){
-    on.exit(eval.parent(call('<-',gn,g)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',gn,g)),error=identity))
   invisible(g)
 }
 
@@ -398,9 +392,7 @@ network.incidence<-function(x, g, ignore.eval=TRUE, names.eval=NULL, ...){
     g<-add.edge(g,tail,head,names.eval=en,vals.eval=ev,edge.check=edge.check)
   }
   #Patch up g on exit for in-place modification
-  if(.validLHS(gn,parent.frame())){
-    on.exit(eval.parent(call('<-',gn,g)))
-  }
+  on.exit(tryCatch(eval.parent(call('<-',gn,g)),error=identity))
   invisible(g)
 }
 
diff --git a/man/network-internal.Rd b/man/network-internal.Rd
index 7ccc140..252237f 100644
--- a/man/network-internal.Rd
+++ b/man/network-internal.Rd
@@ -22,6 +22,7 @@ network.}
 
 \item{y}{a network or something coercible to one.}
 
+\item{\dots}{further arguments passed to or used by methods.}
 }
 \description{
 Internal network functions.